| Severity: |
normal
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CC: |
adruab, Andreas.Glowatz, andreg, bobm75, boris, c.pop, cdfrey, charles, christophe.guillon, cxl, czang, d.bonekaemper, danfuzz, davids, davmac, devin, djk, dmeggy, duraid, evgeny, ezharkov, fabdouze, fm, gcc-bugs, gcc, gcc, ghouston, gino, gopalv82, grigory_zagorodnev, hayim, horst.lehser, hurbain, ja2morri, jason.elbaum, jfran, jochang, larschri, lindsayd, linuxadmin, lucho, l_heldt, micis, mike, mor_gopal, noaml, pgonzalez, pierre.chatelier, pjh, rarob, renzo, rick.ju, spelis, steffen.zimmermann, steger, strasbur, sumii, thomas.anders, warp, zengpan, zybi
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Following code sets a 4 32-bit int sse vector to 1 for all elements and extracts one int out of the vector. g++ returns an incorrect result when compiling with -O2 or -O3 but not with -O1 or -O0 // ----------------------- #include <stdio.h> #include <emmintrin.h> int main() { __m128i ix = _mm_set1_epi32(1); int res = ((int*)&ix)[1]; printf("results: %i\n", res); } // ----------------------- compiled with: $ g++-4.1.0 -O2 -msse2 expected result: 1 actual result: -1209151480 similar misbehavior by gcc-3.4.5 acutal result: 134513897 $ g++-4.1.0 -v Using built-in specs. Target: i686-pc-linux-gnu Configured with: /var/tmp/portage/gcc-4.1.0/work/gcc-4.1.0/configure --prefix=/usr --bindir=/usr/i686-pc-linux-gnu/gcc-bin/4.1.0 --includedir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.0/include --datadir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0 --mandir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0/man --infodir=/usr/share/gcc-data/i686-pc-linux-gnu/4.1.0/info --with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/4.1.0/include/g++-v4 --host=i686-pc-linux-gnu --build=i686-pc-linux-gnu --disable-altivec --enable-nls --without-included-gettext --with-system-zlib --disable-checking --disable-werror --disable-libunwind-exceptions --disable-multilib --disable-libmudflap --disable-libssp --enable-java-awt=gtk --enable-languages=c,c++,java,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu Thread model: posix gcc version 4.1.0 (Gentoo 4.1.0)